Unix Timestamp Converter

What is Unix time?

A Unix timestamp, also called epoch time or POSIX time, is a count of the seconds that have passed since midnight UTC at the start of 1 January 1970, the Unix epoch. A single integer identifies one moment worldwide, which makes it a favorite for databases, log files, APIs and file systems.

Unix time treats every day as exactly 86,400 seconds and does not count leap seconds. The clock therefore repeats or skips a second at a leap second instead of showing 23:59:60, and the conversion between timestamps and calendar dates stays simple arithmetic.

timestamp = days since 1970-01-01 × 86,400 + seconds since midnight UTC

Converting a timestamp to a date

Leave the mode on Timestamp to Date & Time and enter the number of seconds. Two lines appear: the UTC date in the familiar HTTP style (for example Tue, 14 Nov 2023 22:13:20 GMT) and the same moment in your device's own format and time zone.

• Seconds, not milliseconds. Ten-digit values are seconds. A 13-digit value such as 1700000000000 is in milliseconds, so divide it by 1,000 first; entered as it is, it would land in the year 55840.
• Fractions are dropped. 1.5 is displayed as the whole second 1.
• Before 1970. Negative numbers count backwards from the epoch: -1 is 23:59:59 UTC on 31 December 1969.
• Empty field. A blank box is read as 0, which is the epoch itself.
• Range. Dates run to the year 275760 (timestamp 8,640,000,000,000). Beyond that the tool shows Invalid Date.

Converting a date to a timestamp

Choose Date & Time to Timestamp, fill in the year, month and day, and optionally the hour, minute and second. Pick UTC to read the date as Coordinated Universal Time, or Local Time to read it in the time zone of your device, with its daylight-saving rules for that date.

• The year must be 1970 or later; an earlier year leaves the previous answer unchanged.
• Empty hours, minutes and seconds count as zero, so a date alone means midnight.
• Enter the month and day too. A blank month or day is treated as 0, which steps one back: month 0 is December of the previous year and day 0 is the last day of the previous month. A year on its own, such as 2026, gives 30 November 2025.
• Overflowing values roll over: month 13 becomes January of the next year, hour 24 is midnight of the next day, and 90 minutes is one hour and thirty minutes.
• Decimals are truncated, so 15.9 as a day is read as 15.

Worked example. Take 29 February 2024, 13:45:10 UTC. From 1 January 1970 to 1 January 2024 there are 54 × 365 + 13 leap days = 19,723 days. Adding 31 days of January and 28 more to reach 29 February gives 19,782 days. Then 19,782 × 86,400 = 1,709,164,800 seconds. The time of day adds 13 × 3,600 + 45 × 60 + 10 = 49,510 seconds, so the timestamp is 1,709,214,310, matching the converter.

Notable timestamps

The last two rows are the limits of a signed 32-bit integer. Systems that still store time in 32 bits run out after 03:14:07 UTC on 19 January 2038 and wrap around to 1901. This is the year 2038 problem; 64-bit timestamps, now standard, push the limit billions of years away.

Getting the current timestamp in code

Common pitfalls

• Mixing seconds and milliseconds. JavaScript and Java often use milliseconds, most other systems seconds. Count the digits.
• Forgetting the time zone. A timestamp has no zone, but a calendar date does. Decide whether you mean UTC or local time before converting a date.
• Assuming local output is the same everywhere. The locale line follows your device settings, so two people may see different text for the same timestamp.

For hour-and-minute arithmetic use the time converter, to compare clock times between cities the time zone converter, and to turn clock-in times into billable hours the timesheet converter. The days between dates calculator counts the whole days between two calendar dates.